From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6DF7CC433E2 for ; Tue, 1 Sep 2020 16:08:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4ADF7204EC for ; Tue, 1 Sep 2020 16:08:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598976481; bh=VWSllKKk+WEtklV8DWhZEO/PBAyxwv1cjVK8UBP56/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=P2f1r9b4lx0fDUndnky9RZrkv+W8XWvdISkknxj37YNg6BKyHo7shv1APcc4rndaT qk1mbykeQNkATbcP/qIlKhuvilRKoibLWoTlg6PRoT7DUwtJNWPfsAtk0XHeyDhNhG LyTObrXIIW3pOhU66kJOmFW8QpsbBNf3MvsHYDjo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728367AbgIAQHx (ORCPT ); Tue, 1 Sep 2020 12:07:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:49936 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728815AbgIAPjm (ORCPT ); Tue, 1 Sep 2020 11:39:42 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 65100205F4; Tue, 1 Sep 2020 15:39:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598974782; bh=VWSllKKk+WEtklV8DWhZEO/PBAyxwv1cjVK8UBP56/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zZTAJYEuOFJfGT425oIKudyUeZkvm12Odst7ozNUHiMOepSutSiEXIMvB/EWpVbw7 7Ferpvm3NUxQEc8J1qlMzk5G3200VG31msHUhbHDFGITxvSfXwxpdvjV3UYJwo+jUN m8EpmNmqWopMWBxBg9d+KqBmN6Lkq6uDIgC/hVBM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xiubo Li , Jeff Layton , Ilya Dryomov , Sasha Levin Subject: [PATCH 5.8 058/255] ceph: fix potential mdsc use-after-free crash Date: Tue, 1 Sep 2020 17:08:34 +0200 Message-Id: <20200901151003.503306422@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200901151000.800754757@linuxfoundation.org> References: <20200901151000.800754757@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xiubo Li [ Upstream commit fa9967734227b44acb1b6918033f9122dc7825b9 ] Make sure the delayed work stopped before releasing the resources. cancel_delayed_work_sync() will only guarantee that the work finishes executing if the work is already in the ->worklist. That means after the cancel_delayed_work_sync() returns, it will leave the work requeued if it was rearmed at the end. That can lead to a use after free once the work struct is freed. Fix it by flushing the delayed work instead of trying to cancel it, and ensure that the work doesn't rearm if the mdsc is stopping. URL: https://tracker.ceph.com/issues/46293 Signed-off-by: Xiubo Li Reviewed-by: Jeff Layton Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin --- fs/ceph/mds_client.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 946f9a92658ab..903b6a35b321b 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -4285,6 +4285,9 @@ static void delayed_work(struct work_struct *work) dout("mdsc delayed_work\n"); + if (mdsc->stopping) + return; + mutex_lock(&mdsc->mutex); renew_interval = mdsc->mdsmap->m_session_timeout >> 2; renew_caps = time_after_eq(jiffies, HZ*renew_interval + @@ -4660,7 +4663,16 @@ void ceph_mdsc_force_umount(struct ceph_mds_client *mdsc) static void ceph_mdsc_stop(struct ceph_mds_client *mdsc) { dout("stop\n"); - cancel_delayed_work_sync(&mdsc->delayed_work); /* cancel timer */ + /* + * Make sure the delayed work stopped before releasing + * the resources. + * + * Because the cancel_delayed_work_sync() will only + * guarantee that the work finishes executing. But the + * delayed work will re-arm itself again after that. + */ + flush_delayed_work(&mdsc->delayed_work); + if (mdsc->mdsmap) ceph_mdsmap_destroy(mdsc->mdsmap); kfree(mdsc->sessions); -- 2.25.1